I think it’s pretty clear. There are 2 separate versions of every animal: humanoid/sentient and original/non-sentient. Although 2 different animal species may have a similar appearance, this is purely cosmetic and they are not the same.

What does this tell us about the PPCU?

1. ⁠Most likely there has been some genetic experimentation going on. Either a single original intelligent species created a new group of genetically modified animals that shared similar levels of intelligence OR there were always a number of sentient species that coexisted and then one of them created genetically modified non-sentient versions of them all.
2. ⁠Perhaps the original sentient species was humans. What if humans created modified versions of animals and now humans have gone but their creations remain? This makes sense because they look humanoid. Could also be apes in general though.
3. ⁠Maybe humans were killed and wiped out by the animals that they created. An act of revenge? Or simply because they wanted control? Humans may still be out there. I suspect the next season will include Peppa discovering an underground railroad situation.